1. Cross-Reference to Related Applications
Reference is made to copending, commonly assigned U.S. patent application Ser. No. 063,882, filed Jun. 19, 1987, now U.S. Pat. No. 5,047,955, in the names of Shope et al, and copending, commonly assigned U.S. patent application Ser. No. 064,739, filed Jun. 22, 1987, now U.S. Pat. No. 4,882,686 in the name of Gretter.
2. Field of the Invention
The present invention relates to non-impact printing apparatus for recording on a moving recording medium, and particularly to a resequencing line store device for resequencing sequential line data to be recorded on a recording medium.
3. Brief Description of the Prior Art
In the prior art as exemplified by U.S. patent application Ser. No. 064,739, "Printing Apparatus With Improved Data Formatting Circuitry", filed Jun. 22, 1987, now U.S. Pat. No. 4,882,686, printing apparatus is described which comprises a multiplicity of individually addressable and energizable point-like radiation sources, such as light-emitting diodes (LED's), arranged in row(s) for exposing points upon a photoreceptor during movement thereof relative to and in a direction normal to the row(s). Driver circuits are provided for simultaneously energizing the radiation sources responsive to respective data bit input signals applied to the driver circuits during an information line period. The print or recording head includes a support upon which are mounted chips placed end to end and upon each of which are located a group of LED's. The driver circuits are incorporated in other chips located to each side of the linear array of LED's. The driver chips are provided to both sides of the LED array and the drive circuitry is alternately interleaved. The linear array with respective driver circuits thereby collectively forms a LED bar. The print or recording head is typically a multi-channel device; e.g., the data is supplied to the several driver circuits in the print head on multiple data lines or channels. The number of such channels is typically two or four, and sometimes higher numbers depending upon the print head configuration.
The driver circuits in this apparatus each include a shift register for serially receiving data-bit signals and for driving respective LED's in accordance with the data or image signals. The shift registers on adjacent chips are coupled together to function as a single "shift register assemblage" so that the data bits (image signals) flow serially into the shift registers in the shift register assemblage under clock control. Because of the extremely small separation distance between the individual LED's, the conductive lines to each LED are arranged at the periphery of the LED group in an odd-even pattern. At one side of a LED bar is arranged the conductive lines or foils which lead to the shift registers for the even-numbered LED's, and at the opposing side are the lines similarly arranged to the registers for the odd-numbered LED's. Moreover, the total number of registers in each side is divided into a high set and a low set of registers and thus two correspondingly-named data lines or channels supply each side. Hence, data must be provided to the high and low shift registers located to one side of the LED's, as appropriate for the odd-numbered LED's, and similarly to the shift registers on the other side. This arrangement speeds the flow of data to the shift registers in that the odd and even data bits go simultaneously to respective odd and even shift register assemblages. While data is being shifted down one set of odd shift registers, additional odd bits of data simultaneously are being shifted down other odd shift register assemblages.
However, in such an apparatus, the image signals are resequenced by reading them from a buffer memory means to an intermediate register means. Thus, the data must be first stored in the memory means in sequential order and then extracted from the memory means so as to be placed in the intermediate register means. The data is then extracted by selectively addressing the memory means, and the resequencing requires a particular addressing scheme to properly address the necessary data bits retained in the memory means.
The data management for this type of apparatus may be complex or simple depending upon the arrangement of the data. Generally in applications having data outputted by a raster image processor (RIP) intended to be written by a laser beam, data management for directing such data to a multiple array print head presents some difficulties. This is due to the sequential order in which the data is provided, particularly in applications having a printer control system operated from a RIP as is described in copending, commonly assigned U.S. patent application Ser. No. 063,882, filed Jun. 19, 1987, now U.S. Pat. No. 5,047,955 in the names of Shope et al. In a laser exposure device that employs, for example, a rotating polygon to expose a line in the mainscanning direction, the data is sequenced first pixel first, and so on until the last pixel on the line. The data stream may be reformatted into multi-bit parallel words for retention in various frame or page data buffers.
It has been found, therefore, that a need exists for resequencing circuitry for converting an image data stream of sequential order into multiple data streams suitably organized for use by print head or other devices which receive data in multiple data streams partitioned in a high-and-low, odd-and-even numbered data bit format.